A braking force holding control device is known that holds braking force when a vehicle has been stopped on a slope so as to inhibit the vehicle from sliding back down the slope prior to when driving force is transmitted for traveling the vehicle again. However, if the timing at which holding of the braking force is released and the timing at which driving force is transmitted do not match, difficulties may occur. For example, the vehicle may not be reliably stopped from sliding back down the slope, or on the other hand, if the braking force is still being held when the driving force is generated, the vehicle may start to move in a manner that the driver feels to be scratchy.
To address these difficulties, Japanese Patent Application Publication No. JP-A 64-60458 describes a braking force holding control device that is equipped with a clutch sensor that can detect the timing at which the clutch engages. By using the clutch sensor to detect a stroke amount of the clutch, it is possible to detect the timing when the clutch engages. Holding of the braking force can then be released in accordance with this timing. Similarly, the device described in Japanese Patent Application Publication No. JP-A 63-68448 includes a half-engaged clutch position sensor that can detect a half-clutch position. By detecting whether the clutch is in the half-clutch position, it is possible to provide assistance for when the vehicle starts to move on a slope. The half-engaged clutch position sensor is able to change the position detected as the half-clutch position in accordance with the amount of wear of the clutch plates.
However, both of the devices described in Japanese Patent Application Publication No. JP-A 64-60458 and JP-A 63-68448 require a sensor that can detect the position of the clutch in order to determine the timing at which the braking force needs to be released. This causes various difficulties such as the fact that a larger number of components have to be used in the respective braking force holding control devices.
To avoid such problems, the braking force could be held for a predetermined holding time, and this holding time could be set in accordance with a distribution showing the time taken for different users to engage the clutch. For example, among vehicle users, there are some individuals who engage the clutch in a short period of time (hereinafter referred to as “fast clutch engagement”) and some individuals who engage the clutch very slowly (hereinafter referred to as “slow clutch engagement”). A distribution of the timing of clutch engagement for these different types of user could be established. Then, the holding time for the braking force could be set as the clutch engagement time that is most common among the users. A braking force holding control device using the above-described structure would be suitable for general use.
However, if the holding time is set in this manner, holding of the braking force is not released at a timing that accords with the timing of the clutch engagement of each individual user. As a result, if a vehicle equipped with this type of braking force holding control device were to start moving on a slope, an individual who performs fast clutch engagement would feel that his/her vehicle was starting to move in a scratchy manner, while an individual who perform slow clutch engagement would find that his/her vehicles slides back down the slope.